freeCodeCamp/guide/english/mathematics/trigonometry/trigonometric-identities/index.md

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Trigonometric Identities

Trigonometric Identities

Trigonometric Identities are equalities that involve trigonometric functions. Trigonometric functions are functions of an angle that relate the angles of a triangle to the lengths of its sides (e.g. sine, cosine, and tangent). Trigonometric Identities are true for every value of the variables where both sides of the equality are defined.

Whenever expressions involving trigonometric functions need to be simplified, Trigonometric Identities are very useful.

List of Trigonometric Identities

  • Angle Addition Formulas
  • Double-Angle Formulas
  • Half-Angle Formulas
  • Harmonic Addition Theorem
  • Mollweide's Formulas
  • Morrie's Law
  • Multiple-Angle Formulas
  • Newton's Formulas
  • Prosthaphaeresis Formulas
  • Simpson's Formulas
  • Sine-Tangent Theorem
  • Trigonometric Addition Formulas
  • Trigonometric Power Formulas
  • Trigonometric Series Formulas
  • Trigonometry Angles
  • Trigonometry Angles--0
  • Trigonometry Angles--Pi/2 - Pi/32
  • Wallis Cosine Formula
  • Wallis Formula
  • Wallis Sine Formula
  • Weierstrass Substitution
  • Werner Formulas

Cosines and Sines Around the Unit Circle

Cosine and Sine are the Unit Circle

Other Resources